Transformer voltage regulating arrangement



March 23, 1954 s, sTlMLER 2,673,321

TRANSFORMER VOLTAGE REGULATING ARRANGEMENT Original Filed Nov. 17, 1948 l I Primary 9 7 mmzm kcondalg 5 n z'ndz'qq. L i i .0 b d I 6 (Z ZF IF I0 II 9a X 915 E g I ga/g NX IN V EN TOR.

H L? Stmlen lyi- M H15 ATTORNEY) Patented Mar. 23, 1954 TRANSFORMER VOLTAGE REGULATING ARRANGEMENT Saul Stimler, Brooklyn, N. Y., assignor to Westinghouse Air Brake Company, a corporation of Pennsylvania Original application November 17, 1948, Serial No. 60,533. Divided and this application tober 19, 1950, Serial No. 191,018

3 Claims. 1

My invention relates to alternating electric current transformer voltage regulating arrangements, and particularly to arrangements for at times reducing the voltage generated in the secondary winding of a. transformer in order to limit the current supplied to a load by the transformer.

The present application is a division of my copending application, Serial No. 60,533, filed November 17, 1948, now Patent #2,598,617, for Alternating Electric Current Transformers.

For some uses, such, for example, as in railway track circuits, it is desirable to limit or hold down the current output from the secondary winding of a, transformer to a greater extent than can be done by means of fixed impedance. In an alternating current track circuit which embodies a limiting resistor or reactor of fixed impedance, the current drawn by the track circuit may increase considerably as a train moves over the track section from the entering or relay end to the leaving or transformer end of the section, especially if the section is a long one. If the primary winding of the track transformer is energized by current from a direct current source passed through contacts of a vibrating device, such, for example, as a tuned reed alternator, the contacts of the tuned alternator may be rapidly eroded because of the large increase in current taken at times by the track circuit.

One feature of my invention is therefore the provision of novel and improved circuit arrangements, embodying a transformer having a control winding as well as a primary winding'and a secondary winding, for automatically restraining or holding down an increase in current taken by an output circuit which includes the secondary winding of the transformer.

I shall describe two forms of circuit arrangements embodying my invention, and shall then point out the novel features thereof in claims. In the accompanying drawings, Fig. 1 is a diagrammatic view showing a transformer which comprises a core having four legs, a primary winding, a secondary winding, and a control winding; Fig. 2 is a diagrammatic view showing a circuit arrangement employing the transformer shown in Fig. 1; and Fig. 3 is a modification of the circuit arrangement shown in Fig. 2, also embodyingv the transformer shown in Fig. 1.

Similar reference characters refer to similar parts each of the views.

Referring first to Fig. 1, a transformer, desig-- nated as a whole by the reference character IE, i shown provided with a core having a first leg I, a second leg 2, a third leg 3, a fourth leg 4, an end 5 by means of which a given end of each of the legs I, 2, 3, and 4 is connected with a given end of each of the other legs, and an opposite end 6 by means of which the opposite end of each of the legs I, 2, 3, and 4 is connected with an opposite end of each of the other legs. A primary winding 1 is wound around leg 2, and a secondary winding 8 is wound around legs 3 and 4. A control winding consists of two equal portions 9a and 9b, one of which, portion 9a,, is wound around leg 3, and the other of which, portion 9b, is wound around leg 4 which is similar to leg 3.

Primary winding 1, when energized, sends magnetic flux through core legs I, 4, and 3 in multiple, by paths shown in dash lines designated by the reference characters aa, bb, and dd, respectively.

Control winding portions 9a and 9b are connected in series with each other to a source of control current, and are so wound on legs 3 and 4 that they work together to send magnetic flux through legs 3 and 4 in series, by the path shown in the dash line designated by the reference character c-c. If the current in the control winding Ila-9b increases, so that more flux follows the path 0-0 in legs 3 and 4, the core material in legs 3 and 4 will become more saturated, so that less flux can be sent by primary winding I through the paths b--b and d-d, and more flux will be sent by winding I through the path aa.

The magnitude of the voltage generated in secondary winding 8 of transformer IF depends on the magnetic flux passing along paths b-b and d-d, so when the flux in these paths decreases due to an increase of flux in path cc because of an increase of current in the control winding, the voltage generated in secondary winding 8 will be reduced or held down.

In Fig. 2, a transformer IF, constructed as shown in Fig. 1, is energized from a suitable source of alternating current, having terminals BX and NX, connected across primary winding 1. A second transformer 25 has a primary winding I0 'connectedin series with secondary winding8 of transformer IF which supplies current to a load L. Transformer 2F has also a secondary winding II which is connected in a control circuit in series with control winding 9a-9b.

If the current taken by load L increases, a higher voltage will be generatedin winding I I'of transformer 2F, so that more current will be supplied to the control winding Sic-9b. The flux in path e-c produced by winding Set-9b will then increase, and therefore the magnetic flux in paths 11-49 and cld will decrease, so that the voltage generated in secondary winding 8 of transformer IF will be reduced.

In Fig. 3, a transformer IF, constructed as shown in Fig. 1, is energized from a suitable source of unidirectional current, such as a battery Q, through contacts of a vibrator TA. The vibrator TA may be of the well-known tuned reed alternator type having a control winding m, a movable contact element I2, fixed contact points I3 and I4, and a control contact point I5. Movable contact element I2, in the normal or deenergized position, in which it is shown in the drawing, engages control contact point 15.

The circuit by which control winding m of tuned alternator TA is periodically energized passes from the positive terminal of battery Q, through movable contact element I2, control contact point I5, and winding m, back to battery Q, With winding m energized by the circuit just traced, movable contact element I2 will be moved toward the right, as shown in the drawing, so it will disengage control contact point I5, and will engage contact point I3. Winding m is thus deenergized because of the disengagement of movable contact element I2 from control point I5, and therefore element I2 will now swing to the left, and will again engage control contact point I5, and will also engage contact point I4. The cycle of operation just described is then consecutively repeated, causing movable contact element I2 to repeatedly engage fixed contact points I3 and I4 alternately.

When contact element I2 engages contact point I3, a circuit is completed passing from battery Q, through contact element I2, contact point I3, terminal 11. of transformer IF, the portion of primary winding 1 of transformer IF between terminal u and a mid point i, and control winding Ila- 9b, back to battery Q. When contact element I2 engages contact point I4, a second circuit for primary winding 1 is completed, passing from the positive terminal of battery Q, through contact element I2, contact point I4, terminal of transformer IF, the opposite portion of winding I of transformer IF between terminal to and mid point i, and control winding 9a9b, back to battery Q.

It follows, that the two portions of winding I are repeatedly energized alternately by current of opposite polarity, so that magnetic flux is passed by the primary winding 1 through the paths 17-?) and d-d which link with secondary winding 8, and therefore a voltage is generated in winding 8.

Rails I6 and Ilia. of a stretch of railway track are shown divided by insulated joints IT to form a track section T. A track circuit is shown for section T, including secondary winding 8 of transformer IF connected across the rails adjacent one end of the section, and a track relay, designated by the reference character TR, connected across the rails adjacent the opposite end of the section.

When the current taken from secondary winding 8 increases as a train moves over section T from left to right, as shown in the drawing, more current is taken from battery Q by primary winding 1. The current passing through winding 9a 9b is thereby also increased, and causes more magnetic flux to pass through the path c-c, and less flux to pass through the paths b-b and 4 d-d. With less flux in paths 12-1) and d-d, the voltage generated in secondary winding 8 of transformer IF is reduced, and therefore less current is required from battery Q.

It follows, that the current required to pass through contacts I2-I3 and I2I4 is thereby reduced, and there will be less erosion of these contacts.

Although I have herein shown and described only a few forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims Without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, an alternating electric current transformer comprising a core and a primary winding for passing magnetic flux through said core and also a secondary winding energizable by magnetic flux in said core and a control winding for regulating the magnetic flux passed through said core by said primary winding, a source of unidirectional current, means for repeatedly supplying pulses of current of normal and reverse polarity alternately from said source of unidirectional current to said primary winding through said control winding, and a load circuit including said secondary winding.

2. In combination, an alternating electric current transformer comprising a core and a primary winding for passing magnetic flux through said core and also a secondary winding energizable by magnetic flux in said core and a control winding for regulating the magnetic fiux passed through said core by said primary winding, a source of unidirectional current, a vibrator contact, means for repeatedly moving said contact to first and second control positions alternately, a circuit including said contact in its first position for supplying a pulse of current from said source through one end of said primary winding and thence from a mid point of said primary winding through said control winding, a second circuit including said contact in its second position for supplying a pulse of current from said source through the opposite end of said primary winding and thence from said mid point of said primary winding through said control winding, and an output circuit including said secondary winding.

3. In combination, an alternating electric current transformer comprising a core and a primary winding for passing magnetic flux through said core and also a secondary winding energizable by magnetic flux in said core and a control winding for regulating magnetic flux passed through said core by said primary winding, means for repeatedly supplying current of alternately normal and reverse polarity to said primary winding in series with said control winding according to the magnitude of current in said output circuit, and an output circuit including said secondary windmg.

SAUL STIMLER.

References Cited in the file of this patent UNITED STATES-PATENTS Number Name Date 2,117,820 Hagan May 1'7, 1938 2,215,822 Hagan Sept. 24, 1940 2,364,558 Stocker Dec. 5, 1944 2,467,347 Trucksess Apr. 12, 1949 

